Pfeuffer Josef, Adriany Gregor, Shmuel Amir, Yacoub Essa, Van De Moortele Pierre-Francois, Hu Xiaoping, Ugurbil Kamil
Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, USA.
Magn Reson Med. 2002 May;47(5):903-11. doi: 10.1002/mrm.10154.
Perfusion-based MRI measures cerebral blood flow (CBF) at the capillary level and can be used for functional studies based on the tight spatial coupling between brain activity and blood flow. Obtaining functional CBF maps with high spatial resolution is a major challenge because the CBF signal is intrinsically low and the SNR is critical. In the present work, CBF-based functional imaging was performed at a considerably smaller voxel size than previously reported in humans. High-resolution CBF maps were obtained with voxel sizes as small as 0.9 x 0.9 x 1.5 mm(3) in the human brain. High sensitivity was made possible by signal-to-noise gains at the high magnetic field of 7 T and by using a novel RF combination coil design. In addition, a reduction of the field-of-view was critical to achieve 0.9-mm in-plane resolution with gradient-echo echo-planar imaging in a single shot. Functional CBF data were compared with functional BOLD data to reveal that, for CBF, large contrast- to-noise gains were obtained at high spatial resolution, indicating that the functional CBF response was more localized. High-resolution functional CBF imaging is significant for neuroscience research because it provides better localization and more specific information than BOLD for monitoring brain function.
基于灌注的磁共振成像在毛细血管水平测量脑血流量（CBF），并且可用于基于脑活动与血流之间紧密空间耦合的功能研究。获取具有高空间分辨率的功能性CBF图是一项重大挑战，因为CBF信号本身较低，且信噪比至关重要。在本研究中，基于CBF的功能成像所采用的体素大小比之前在人体中报道的要小得多。在人脑内以低至0.9×0.9×1.5 mm³的体素大小获得了高分辨率CBF图。通过在7 T高磁场下的信噪比增益以及采用新型射频组合线圈设计实现了高灵敏度。此外，减小视野对于在单次梯度回波平面回波成像中实现0.9 mm的平面分辨率至关重要。将功能性CBF数据与功能性BOLD数据进行比较后发现，对于CBF而言，在高空间分辨率下获得了较大的对比噪声增益，这表明功能性CBF反应更具局域性。高分辨率功能性CBF成像对神经科学研究具有重要意义，因为与BOLD相比，它在监测脑功能方面提供了更好的定位和更具体的信息。
